Who has the fastest warplane? Russia tests another supersonic T-50 fighter.

Russian Prime Minister Vladimir Putin walks after inspecting a new Russian fighter jet after its test flight in Zhukovksy, outside Moscow, June 17, 2010. The new jet, Sukhoi T-50 fighter, is Russia's response to the US F-22 Raptor.

Russia successfully tested a second prototype of its revolutionary new "fifth-generation" fighter plane Thursday, a futuristic, ultrafast, and stealthy warbird that may be in the possession of the Russian Air Force by 2013.

If Russian claims about the Sukhoi T-50 multirole fighter are true, then the country that has made do with Soviet-era arms for the past two decades is poised to roar into the 21st century with a cutting-edge weapons system that is so advanced and complex that only the US has been able to field one.

China recently tested its own version of a stealth fighter, but Russian experts say China's J-20 lacks many characteristics of the so-called fifth-generation warplanes, which are known for sustained supersonic cruise, over-the-horizon radar visibility, integrated weapons and navigation systems managed by artificial intelligence, and high-performance frames made from space-age materials.